The conventional way to use a lock is prepare suitable number of keys to families so as to unlock the lock, however, the lock is not safe when one of the keys is lost and most of the users will change a new lock for safety reason. The replacement of the locks sometimes cost a lot of money and is not convenient for the users.
FIGS. 1 to 3 show a conventional lock which generally comprises a housing 10 and a core 20, the housing 10 has multiple top pin holes 101 and the core has multiple bottom pin holes 201 which are in communication with the top pin holes 101. Multiple pin units 30 are installed in the top and bottom pin holes 101, 201. A cover 102 is mounted to the top pin holes 101 and the housing 10 has multiple grooves 103 so as to be cooperated with the cover 102. The core 20 has a key hole 202 in one end thereof and the other end of the core 20 has a latch 203.
In normal condition, the key is inserted into the core 20 via the key hole 202 and the notches of the key accommodate the pin units 30 to align the outer surface of the core 20 with the ends of the top and bottom pin holes 101, 201, such that the latch 203 is operated by rotating the key. When the correct key is lost, the pins can be replaced, as shown in FIG. 2, by first removing the cover 102 from the grooves 103 and the pin units 30 are removed from the top and bottom pin holes 101, 201. The suitable pin units 30 are then installed to the top and bottom pin holes 101, 201 according the arrangement of the notches of a new key. The cover 102 is again engaged with the grooves 103 to obtain a new lock.
Nevertheless, when replacing the pins, the pin units 30 are removed from the core 20 only when the top and bottom pin holes 101, 201 are in alignment with each other. Once the diameters of the top and bottom pin holes 101, 201 are different, or the top and bottom pin holes 101, 201 are not in alignment to each other, the pin units 30 are stocked in the lock and the replacement cannot be successfully made. The users are difficult to check whether or not the top and bottom pin holes 101, 201 are in alignment to each other from the top pin holes 101. The new pin units 30 are also not easily to be properly installed into the bottom pin holes 201 so that it is difficult for the users to replace the pins. Besides, the cover 102 is difficult to be removed from the grooves 103, even if only one set of the pin unit 30 is to be replaced, the cover 102 is stilled required to be removed and other pin units 30 may drop out from the lock to further increase the time required to replace the pin units 30.
The present invention intends to provide a lock with replaceable bottom pins, and the replacement is easy.